The present invention relates to a picture information display device of a picture information storage/retrieval apparatus and, more particularly, to a picture information display device in which a display area of the display unit is effectively used and display operation for displaying picture information is simplified.
A picture information storage/retrieval apparatus has been recently developed and made commercially available in which picture information on documents in offices is scanned by two-dimensional scanning and such picture information is stored in a storage unit such as an optical disk unit, and in which desired picture information is retrieved as needed and is printed by a hard copying unit.
In the picture information storage/retrieval apparatus of the type described above, the retrieval speed differs from the storage speed, so that picture information corresponding to the unit amount (page information) is temporarily stored in a page buffer memory. The picture information in the page buffer memory is monitored on a picture information display unit which comprises a display interface, a CRT display and the like.
The page buffer memory has a memory area corresponding to 2048 bits.times.2800 lines, as shown in FIG. 1. However, since the refresh memory only has a memory area corresponding to 1024 bits.times.700 lines, all picture information cannot be displayed at the CRT display at once.
In a conventional apparatus, a size converting circuit is arranged in the display interface. The picture information read out from the page buffer memory is compressed by 1/4. The compressed picture information is then stored in the refresh memory so as to display all the picture information at the CRT display at once.
However, in this case, the reductive ratio is fixed regardless of the size of picture information. The size of picture information displayed at the CRT display cannot actually be standardized. As a result, the display area cannot be effectively utilized. When the picture information includes small characters, these characters can often not be recognized on the CRT display screen, thus degrading resolution of the picture image.
In order to solve the above problems, a cursor function is provided in the display interface in addition to the size converting circuit. As shown in FIG. 2B, the size of picture information is reduced to 1/4 and is temporarily displayed at the CRT display. Picture information corresponding to a cursor S (frame indicated by the alternate long and short dashed line) as a zoom-up area provided on the CRT display screen is read out from the page buffer memory and is reduced to 1/2. The reduced picture information is then stored in the refresh memory. As shown in FIG. 2C, half of the picture information can be displayed. This arrangement improves the resolution as compared with the 1/4 reduction of picture information.
However, in this case, if the retrieval rate from the page buffer memory is defined as 6 Mbits/sec, the picture information corresponding to the cursor S is displayed in 0.43 sec (.apprxeq.2048.times.1400/6.times.10.sup.6), thus resulting in a slow display speed.